US20050101152A1 - Method of manufacturing flotox type eeprom - Google Patents
Method of manufacturing flotox type eeprom Download PDFInfo
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- US20050101152A1 US20050101152A1 US10/797,127 US79712704A US2005101152A1 US 20050101152 A1 US20050101152 A1 US 20050101152A1 US 79712704 A US79712704 A US 79712704A US 2005101152 A1 US2005101152 A1 US 2005101152A1
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- oxide film
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- active region
- diffusion region
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/02—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier
- H01L27/04—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body
- H01L27/10—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration
- H01L27/105—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration including field-effect components
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B41/00—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates
- H10B41/30—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by the memory core region
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B41/00—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates
- H10B41/40—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by the peripheral circuit region
Definitions
- the present invention relates to a method of manufacturing a FLOTOX type EEPROM, and particularly to a method of forming a tunnel oxide film region.
- FIGS. 1 through 4 A method of manufacturing a FLOTOX (FLOating gate Tunnel Oxide) type EEPROM, according to a prior art is shown in FIGS. 1 through 4 .
- a field oxide film 2 corresponding to a device or element isolation region is formed on a P type silicon substrate 1 by a LOCOS method.
- boron ions are selectively injected directly below the field oxide film 2 to form a channel stop region 3 .
- N type ions such as phosphorus ions are selectively injected and annealing is effected to form a tunneling implanted region 4 corresponding to an N type diffusion region formed with a tunnel oxide film (see FIG. 1 ).
- the entire surface of the substrate, containing an exposed active region is oxidized about 30 nm to form a gate oxide film 5 .
- a resist 6 is applied thereonto and thereafter subjected to resist patterning to form a tunnel window opening 7 on its corresponding tunneling implanted region 4 (see FIG. 2 ).
- the gate oxide film 5 in the tunnel window opening 7 is etched by a wet etching solution such as hydrofluoric acid to expose part of the tunneling implanted region 4 , followed by removal of the resist 6 .
- the entire surface of the substrate is oxidized about 10 nm to form a locally thin tunnel oxide film 9 having a thickness of about 10 nm and a re-oxidized gate oxide film 10 in a tunnel window region 8 (see FIG. 3 ).
- polysilicon is deposited and subjected to patterning to thereby form a floating gate electrode 11 so as to cover the tunnel window region 8 (see FIG. 4 ).
- a control gate electrode, wiring and the like are thereafter formed, thereby leading to completion of the FLOTOX type EEPROM.
- the thick gate oxide film is processed using the wet etching solution in the tunnel window region etching process for the formation of the tunnel oxide film. Therefore, an opening in an actual tunnel window region becomes large as compared with a resist's pattern, thus leading to a large factor that inhibits a reduction in cell size.
- the present invention has been made in view of the above problems.
- a method of manufacturing an EEPROM according to the present invention.
- a tunneling implanted region and a peripheral active region of an EEPROM memory cell are simultaneously oxidized, and the thickness of an oxide film on the tunneling implanted region is set so as to become thicker than the thickness of each of oxide films on an active region other than the tunneling implanted region by enhanced oxidation of the tunneling implanted region.
- a resist is applied onto the entire surface of a substrate, and a partial tunnel window region on the tunneling implanted region and the resist of an active region in a peripheral transistor forming region other than the memory cell are opened.
- Etching is done until the oxide film in the peripheral transistor forming region is perfectly removed by dry etching. Thereafter, the oxide film remaining in the tunneling implanted region of the memory cell is removed by wet etching, thereby opening and forming a tunnel window region corresponding to a region for forming a locally thin oxide film.
- the oxide film on the tunneling implanted region of the memory cell and the oxide film of the peripheral active region thereon are simultaneously dry etched, control on the detection of an etching end point becomes easy with an increase in etching area. Since the oxide film is formed thicker than the simultaneously formed oxide film of the peripheral active region by use of the enhanced oxidation, the oxide film remains in the tunnel window section upon the end point detection of the dry etching. Hence, substrate etching damage can be reduced. Thus, the scale down or miniaturization of the tunnel window section can be realized by using dry etching while etching damage is being avoided.
- FIG. 1 is a process sectional view showing a method of manufacturing a FLOTOX type EEPROM, according to a prior art
- FIG. 2 is a process sectional view illustrating the FLOTOX type EEPROM manufacturing method according to the prior art following FIG. 1 ;
- FIG. 3 is a process sectional view depicting the FLOTOX type EEPROM manufacturing method according to the prior art following FIG. 2 ;
- FIG. 4 is a process sectional view showing the FLOTOX type EEPROM manufacturing method according to the prior art following FIG. 3 ;
- FIG. 5 is a process sectional view illustrating a method of manufacturing a FLOTOX type EEPROM, according to an embodiment of the present invention
- FIG. 6 is a process sectional view depicting the FLOTOX type EEPROM manufacturing method according to the embodiment of the present invention following FIG. 5 ;
- FIG. 7 is a process sectional view showing the FLOTOX type EEPROM manufacturing method according to the embodiment of the present invention following FIG. 6 ;
- FIG. 8 is a process sectional view illustrating the FLOTOX type EEPROM manufacturing method according to the embodiment of the present invention following FIG. 7 .
- FIGS. 5 through 8 are respectively process sectional views showing an embodiment of the present invention.
- a field oxide film 22 , a channel stop region 23 and a tunneling implanted region 24 are formed on a P type silicon substrate 21 (see FIG. 1 ).
- the whole surface of the substrate which contains an exposed active region, is oxidized about 30 nm to form a gate oxide film 25 of an EEPROM cell section and an oxide film 26 for a peripheral active region (see FIG. 5 ). Since, at this time, the tunneling implanted region 24 is oxidized in advance without being subjected to annealing, the thickness of an oxide film 27 on the tunneling implanted region 24 is formed thicker than other oxide films 25 and 26 each lying in the active region owing to the effect of enhanced oxidation.
- a resist is applied onto the entire surface to form a resist pattern 28 .
- a tunnel window opening 29 and a peripheral transistor region other than a memory cell region are exposed.
- dry etching is carried out until the silicon substrate corresponding to a portion constituting the active region other than the filed oxide film 22 of the peripheral transistor section is exposed (see FIG. 6 ).
- the oxide film 26 in the peripheral transistor region is perfectly removed and the silicon substrate is not exposed. That is, the tunneling implanted region 25 in the tunnel window opening 29 is not subjected to damage of dry etching. Since the oxide film 26 in the peripheral transistor region is also dry etched as well as the oxide film 27 at the tunnel window opening 29 , the detection of an etching end point becomes easy.
- a tunnel window region 30 is formed (see FIG. 7 ).
- the entire surface is oxidized about 10 nm to form a tunnel oxide film 31 and form an oxide film 32 in the peripheral active region (see FIG. 8 ).
- a floating gate electrode, a control gate electrode, wiring and the like are formed by a method similar to the prior art, thus leading to the completion of a FLOTOX type EEPROM.
- the enhanced oxidation of the tunneling implanted region is utilized and the peripheral active portion is made open by dry etching, thereby making it possible to control the end point detection of dry etching. It is therefore possible to make uniform the remaining film of the gate oxide film in the tunnel window portion. Since the remaining film is opened by wet etching, the amount of wet etching can be reduced as compared with the prior art, thus making it possible to reduce variations in the dimension of the diameter of the tunnel window opening.
Abstract
Description
- 1. Field of the Invention
- The present invention relates to a method of manufacturing a FLOTOX type EEPROM, and particularly to a method of forming a tunnel oxide film region.
- 2. Description of the Related Art
- A method of manufacturing a FLOTOX (FLOating gate Tunnel Oxide) type EEPROM, according to a prior art is shown in
FIGS. 1 through 4 . Afield oxide film 2 corresponding to a device or element isolation region is formed on a Ptype silicon substrate 1 by a LOCOS method. After a silicon nitride film employed in a LOCOS process has been removed, boron ions are selectively injected directly below thefield oxide film 2 to form achannel stop region 3. Then, N type ions such as phosphorus ions are selectively injected and annealing is effected to form a tunneling implantedregion 4 corresponding to an N type diffusion region formed with a tunnel oxide film (seeFIG. 1 ). - Subsequently, the entire surface of the substrate, containing an exposed active region is oxidized about 30 nm to form a
gate oxide film 5. Aresist 6 is applied thereonto and thereafter subjected to resist patterning to form a tunnel window opening 7 on its corresponding tunneling implanted region 4 (seeFIG. 2 ). Thegate oxide film 5 in thetunnel window opening 7 is etched by a wet etching solution such as hydrofluoric acid to expose part of the tunneling implantedregion 4, followed by removal of theresist 6. - Then, the entire surface of the substrate is oxidized about 10 nm to form a locally thin tunnel oxide film 9 having a thickness of about 10 nm and a re-oxidized
gate oxide film 10 in a tunnel window region 8 (seeFIG. 3 ). Thereafter, polysilicon is deposited and subjected to patterning to thereby form afloating gate electrode 11 so as to cover the tunnel window region 8 (seeFIG. 4 ). Although not shown in the figure, a control gate electrode, wiring and the like are thereafter formed, thereby leading to completion of the FLOTOX type EEPROM. -
- Japanese Unexamined Patent Publication No. Sho 61(1986)-228672
- Japanese Unexamined Patent Publication No. Hei 4(1992)-145666
- Japanese Unexamined Patent Publication No. Hei 4(1992)-207084
- Japanese Unexamined Patent Publication No. 2001-210730
- In the manufacturing method according to the prior art, however, the thick gate oxide film is processed using the wet etching solution in the tunnel window region etching process for the formation of the tunnel oxide film. Therefore, an opening in an actual tunnel window region becomes large as compared with a resist's pattern, thus leading to a large factor that inhibits a reduction in cell size.
- When the opening of the tunnel window region is performed by a dry etching method, a problem arises in that etching damage which is a problem peculiar to dry etching, occurs, thereby deteriorating the quality of a subsequent tunnel oxide film. Further, a problem arises in that since the open area of the tunnel window region is small, the detection of an end point of dry etching becomes difficult.
- The present invention has been made in view of the above problems. There is provided a method of manufacturing an EEPROM, according to the present invention. According to the method, a tunneling implanted region and a peripheral active region of an EEPROM memory cell are simultaneously oxidized, and the thickness of an oxide film on the tunneling implanted region is set so as to become thicker than the thickness of each of oxide films on an active region other than the tunneling implanted region by enhanced oxidation of the tunneling implanted region. Then a resist is applied onto the entire surface of a substrate, and a partial tunnel window region on the tunneling implanted region and the resist of an active region in a peripheral transistor forming region other than the memory cell are opened. Etching is done until the oxide film in the peripheral transistor forming region is perfectly removed by dry etching. Thereafter, the oxide film remaining in the tunneling implanted region of the memory cell is removed by wet etching, thereby opening and forming a tunnel window region corresponding to a region for forming a locally thin oxide film.
- Since the oxide film on the tunneling implanted region of the memory cell and the oxide film of the peripheral active region thereon are simultaneously dry etched, control on the detection of an etching end point becomes easy with an increase in etching area. Since the oxide film is formed thicker than the simultaneously formed oxide film of the peripheral active region by use of the enhanced oxidation, the oxide film remains in the tunnel window section upon the end point detection of the dry etching. Hence, substrate etching damage can be reduced. Thus, the scale down or miniaturization of the tunnel window section can be realized by using dry etching while etching damage is being avoided.
- While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:
-
FIG. 1 is a process sectional view showing a method of manufacturing a FLOTOX type EEPROM, according to a prior art; -
FIG. 2 is a process sectional view illustrating the FLOTOX type EEPROM manufacturing method according to the prior art followingFIG. 1 ; -
FIG. 3 is a process sectional view depicting the FLOTOX type EEPROM manufacturing method according to the prior art followingFIG. 2 ; -
FIG. 4 is a process sectional view showing the FLOTOX type EEPROM manufacturing method according to the prior art followingFIG. 3 ; -
FIG. 5 is a process sectional view illustrating a method of manufacturing a FLOTOX type EEPROM, according to an embodiment of the present invention; -
FIG. 6 is a process sectional view depicting the FLOTOX type EEPROM manufacturing method according to the embodiment of the present invention followingFIG. 5 ; -
FIG. 7 is a process sectional view showing the FLOTOX type EEPROM manufacturing method according to the embodiment of the present invention followingFIG. 6 ; and -
FIG. 8 is a process sectional view illustrating the FLOTOX type EEPROM manufacturing method according to the embodiment of the present invention followingFIG. 7 . - A preferred embodiment of the present invention will hereinafter be described with reference to the accompanying drawings.
-
FIGS. 5 through 8 are respectively process sectional views showing an embodiment of the present invention. Afield oxide film 22, achannel stop region 23 and a tunneling implantedregion 24 are formed on a P type silicon substrate 21 (seeFIG. 1 ). - Then the whole surface of the substrate, which contains an exposed active region, is oxidized about 30 nm to form a
gate oxide film 25 of an EEPROM cell section and anoxide film 26 for a peripheral active region (seeFIG. 5 ). Since, at this time, the tunneling implantedregion 24 is oxidized in advance without being subjected to annealing, the thickness of anoxide film 27 on the tunneling implantedregion 24 is formed thicker thanother oxide films - Next, a resist is applied onto the entire surface to form a
resist pattern 28. A tunnel window opening 29 and a peripheral transistor region other than a memory cell region are exposed. With theresist pattern 28 as a mask, dry etching is carried out until the silicon substrate corresponding to a portion constituting the active region other than the filedoxide film 22 of the peripheral transistor section is exposed (seeFIG. 6 ). - Since the thickness of a gate oxide film is thicker than other portion at the tunnel window opening 29 at this time, the
oxide film 26 in the peripheral transistor region is perfectly removed and the silicon substrate is not exposed. That is, the tunneling implantedregion 25 in the tunnel window opening 29 is not subjected to damage of dry etching. Since theoxide film 26 in the peripheral transistor region is also dry etched as well as theoxide film 27 at the tunnel window opening 29, the detection of an etching end point becomes easy. - Subsequently, wet etching is done to expose the silicon substrate of the tunnel window opening 29, so that a
tunnel window region 30 is formed (seeFIG. 7 ). After removal of theresist 28, the entire surface is oxidized about 10 nm to form atunnel oxide film 31 and form anoxide film 32 in the peripheral active region (seeFIG. 8 ). Thereafter, although not shown in the drawing, a floating gate electrode, a control gate electrode, wiring and the like are formed by a method similar to the prior art, thus leading to the completion of a FLOTOX type EEPROM. - According to the present embodiment as described above, the enhanced oxidation of the tunneling implanted region is utilized and the peripheral active portion is made open by dry etching, thereby making it possible to control the end point detection of dry etching. It is therefore possible to make uniform the remaining film of the gate oxide film in the tunnel window portion. Since the remaining film is opened by wet etching, the amount of wet etching can be reduced as compared with the prior art, thus making it possible to reduce variations in the dimension of the diameter of the tunnel window opening.
- While the present invention has been described with reference to the illustrative embodiment, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiment, as well as other embodiments of the invention, will be apparent to those skilled in the art on reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.
Claims (4)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP378220/2003 | 2003-11-07 | ||
JP2003378220A JP4345889B2 (en) | 2003-11-07 | 2003-11-07 | Manufacturing method of FLOTOX type EEPROM |
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US20050101152A1 true US20050101152A1 (en) | 2005-05-12 |
US7030025B2 US7030025B2 (en) | 2006-04-18 |
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Application Number | Title | Priority Date | Filing Date |
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US10/797,127 Expired - Fee Related US7030025B2 (en) | 2003-11-07 | 2004-03-11 | Method of manufacturing flotox type eeprom |
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JP (1) | JP4345889B2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2005236062A (en) * | 2004-02-20 | 2005-09-02 | Nec Electronics Corp | Manufacturing method for nonvolatile semiconductor memory apparatus |
JP2006228873A (en) * | 2005-02-16 | 2006-08-31 | Oki Electric Ind Co Ltd | Manufacturing method of nonvolatile semiconductor memory |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4477825A (en) * | 1981-12-28 | 1984-10-16 | National Semiconductor Corporation | Electrically programmable and erasable memory cell |
US4701776A (en) * | 1983-08-29 | 1987-10-20 | Seeq Technology, Inc. | MOS floating gate memory cell and process for fabricating same |
US5491101A (en) * | 1993-11-25 | 1996-02-13 | Matsushita Electronics Company | Manufacturing method of non-volatile semiconductor memory devices |
US6165846A (en) * | 1999-03-02 | 2000-12-26 | Zilog, Inc. | Method of eliminating gate leakage in nitrogen annealed oxides |
US6586765B2 (en) * | 1999-12-20 | 2003-07-01 | Taiwan Semiconductor Manufacturing Company | Wafer-level antenna effect detection pattern for VLSI |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61228672A (en) | 1985-04-02 | 1986-10-11 | Nec Corp | Insulated gate type non-volatile semiconductor memory and manufacture thereof |
JPH04145666A (en) | 1990-10-08 | 1992-05-19 | Nec Corp | Electrically erasable nonvolatile semiconductor memory |
JP2672189B2 (en) | 1990-11-30 | 1997-11-05 | シャープ株式会社 | Nonvolatile random access memory and memory cell array |
JP2001210730A (en) | 2000-01-25 | 2001-08-03 | Oki Electric Ind Co Ltd | Manufacturing method of non-volatile semiconductor storage |
-
2003
- 2003-11-07 JP JP2003378220A patent/JP4345889B2/en not_active Expired - Fee Related
-
2004
- 2004-03-11 US US10/797,127 patent/US7030025B2/en not_active Expired - Fee Related
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4477825A (en) * | 1981-12-28 | 1984-10-16 | National Semiconductor Corporation | Electrically programmable and erasable memory cell |
US4701776A (en) * | 1983-08-29 | 1987-10-20 | Seeq Technology, Inc. | MOS floating gate memory cell and process for fabricating same |
US5491101A (en) * | 1993-11-25 | 1996-02-13 | Matsushita Electronics Company | Manufacturing method of non-volatile semiconductor memory devices |
US6165846A (en) * | 1999-03-02 | 2000-12-26 | Zilog, Inc. | Method of eliminating gate leakage in nitrogen annealed oxides |
US6586765B2 (en) * | 1999-12-20 | 2003-07-01 | Taiwan Semiconductor Manufacturing Company | Wafer-level antenna effect detection pattern for VLSI |
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US7030025B2 (en) | 2006-04-18 |
JP4345889B2 (en) | 2009-10-14 |
JP2005142408A (en) | 2005-06-02 |
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